Il 29/02/2012 17:00, Michael Tokarev ha scritto: > And how it will be a cleanup? > > The whole cow code (and a few others) is not reenterant. Merely > moving this lock/unlock stuff inth actual methods eliminates two > current wrappers in cow_co_write() and cow_co_read(), which are > exactly the same now, and moves this exactly the same code into > actual methods, which has nothing to do with locking - they're > not reenterant, and they deal with internal to the format stuff. > Having this common locking layer on top and _outside_ of the > actual work helps removing irrelevant code from important paths. > Also, it will be too easy to forgot to unlock it there by doing > just "return" somewhere.
It's not very different from leaking memory. It's just the way C works. In the future, you may add unlock around image access like in qcow2, and then an unlock/lock pair would be confusing without the lock/unlock outside. If you are worried about forgetting to unlock, add owner tracking to qemu-coroutine-lock.c, similar to PTHREAD_MUTEX_ERRORCHECK. That would be quite useful. Paolo
